This sensitive bio-monitoring circuit was found in the December 1984 issue of Radio Electronics magazine. The circuit is powered by a 9 V battery and uses a low-impedance headphone output.
The presented circuit is used in Power supply to increase the voltage output. The voltage output...
The frequency of the LC resonant circuit must be the same as that of the crystal and the JFET...
This amplifier can be used for public-address or other applications. Three transistors of the time...